1. Field of the Invention
The present invention relates generally to a fixing structure for a carriage rod and a fixing method thereof, and more particularly to a fixing structure for a carriage rod on which an ink cartridge carriage of a printing machine is supported to reciprocally travel along the carriage rod.
2. Description of the Related Art
It is well known that a paper can be printed with a printing machine such as an inkjet printer. The inkjet printer has an ink cartridge having a print head. The ink cartridge is carried by an ink cartridge carriage to reciprocally move in a direction normal to a paper delivery direction. The ink cartridge carriage is positioned above the surface of a paper that passes through a printing section by a set height, whereby the print head can jet the ink onto the paper to form characters or pictures.
In general, the ink cartridge carriage is supported on a carriage rod to reciprocally travel along the carriage rod for printing operation. The carriage rod has two ends retained on a frame body of the printing machine. In a conventional fixing structure for the carriage rod, the frame body has two sidewalls each of which is provided with a cavity and a clamping mechanism. Two ends of the carriage rod are respectively inserted into the cavities and retained by the clamping mechanisms. As well known by those skilled in this field, the frame body with the cavities and the clamping mechanisms has relatively complicated structures and is manufactured at higher cost.
In another conventional fixing structure for the carriage rod, the two ends of the carriage rod are directly secured to the frame body by means of retainers such as rivets, screws or the like. The sidewalls of the frame body support the carriage rod in cooperation with the retainers. Before the retainers are tightened to lock the two ends of the carriage rod to the frame body, the retainers will not exert a stress onto the carriage rod. Under such circumstance, the carriage rod will not be strained. However, when the retainers are tightened with a torque to secure the two ends of the carriage rod to the frame body, a screw fasten force is applied to the two ends of the carriage rod. At this time, a middle section of the carriage rod will be flexed to change the set height of the ink cartridge carriage reciprocally traveling along the carriage rod through the printing section. This will affect the printing quality. FIGS. 1, 2 and 3 respectively are a force diagram, a shear diagram and a bending moment diagram of a conventional carriage rod, which is tightened to a frame body by means of the retainers and the cooperative sidewalls of the frame body. FIG. 3 shows that the flexed section of the carriage rod is right above the printing section. It can be known from the above that it is not optimal to directly secure the two ends of the carriage rod to the frame body by means of the retainers.
In another conventional fixing structure for the carriage rod, the frame body is formed with slots and provided with slightly resilient cantilevers between the slots. When the two ends of the carriage rod are respectively locked to the cantilevers of the frame body by means of the retainers, the cantilevers are able to partially absorb the deformation of the carriage rod caused by the torque of the retainers. However, with the slots and the cantilevers, the structural strength of the frame body is weakened. As a result, the carriage rod tends to vibrate when the ink cartridge carriage reciprocally travels along the carriage rod in printing operation. Moreover, in some cases, for example, during transfer, delivery or maintenance of the printing machine, the carriage rod is likely to be displaced or damaged due to collision caused by negligence.